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A prothallus, or prothallium, (from Latin pro = forwards and Greek θαλλος (thallos) = twig) is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young gametophyte of a liverwort or peat moss as well.
The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers.They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, and in having life cycles in which the branched sporophyte is the dominant phase.
Over the course of about 6 weeks germination, sex determination and development of gametophytes, fertilization, embryogenesis, organogenesis, and sporophyte growth can all be observed, allowing an incredibly comprehensive study of the life cycle of homosporous ferns in a relatively short time period. [3]
In ferns the gametophyte is a small flattened autotrophic prothallus on which the young sporophyte is briefly dependent for its nutrition. In flowering plants , the reduction of the gametophyte is much more extreme; it consists of just a few cells which grow entirely inside the sporophyte.
In 2009, a molecular phylogenetic study determined that it is, in fact, a fern gametophyte. It was found to be most closely genetically linked to Lomariopsis lineata, though classification as a distinct species was not ruled out. [8] Efforts to induce süsswassertang specimens to form a sporophyte have failed, which may indicate status as a new ...
It has the same life cycle as a typical fern, the sporophyte produces haploid spores by meiosis, which grows into a haploid gametophyte. The gametophyte produce gametes by mitosis. The fertilized egg when develop into the sporophyte by mitosis. The spore is transported by air and water.
Young sporophytes of the common moss Tortula muralis. In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes Sporophytes of moss during spring In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and ...
In seedless vascular plants such as ferns and lycopodiophyta, the term "sporeling" refers to the young sporophyte growing on the gametophyte. These sporelings develop via an embryo stage from a fertilized egg inside an archegonium and depend on the gametophyte for their early stages of growth before becoming independent sporophytes.